Three-phase PWM Rectifier Internal Model Control Based On Sliding Mode Variable Structure

In recent years, the “Green Conversion” of electric energy has been strangelyencouraged among electricity industry，electron industry and power conversionindustry. Traditional rectifying circuit would cause large amounts of harmonicpollution and reactive power, violating new industrial standards. Tri-phase PWMrectifier makes the rectifier has the advantages of sinusoidal input current, low totalharmonic distortion，unity power factor, bi-directional power flow and controllablevoltage. It can fundamentally solve the problems deriving from harmomic wave andreactive power. Therefore，it has a wide proliferation in industrial applicationdomains.This paper will conduct a high-level analysis of tri-phase PWM rectifier, themain contents unfold as follows. Initially, it analysis the topological structure of asingle PWM rectifier module, establishing a mathematical model based on threekinds of commonly used coordinate system. Then, In order to eliminate the shaftcoupling ωL in the two-phase rotating dq, this paper analysis the use of PI regulatorcurrent feed-forward decoupling control process. In view of the complicated processof current feed-forward decoupling, the inner model control is applied to the systemdecoupling, this method has the advantages of simple process, convenient parameteradjustment, and the decoupling process does not rely on accurate system parametersand model parameters. The simulation on the MATLAB’s results show the design ofinternal model controller for PWM rectifier not only depend on the parameters ofsmall, easy to adjust, and has excellent dynamic response performance of the innercurrent loop.In order to improve the voltage outer loop, the sliding mode variable structuretheory is applied to the voltage control system of the outer loop design. It propose ahybrid nonlinear control strategy of sliding mode control and internal model controlbased on sliding mode tracking, voltage outer loop, DC output voltage and outputcurrent loop instructions, internal model control current loop, tracking the instructioncurrent and the net side current sinusoidal voltage. And built the system simulationmodel of three-phase PWM rectifier based on MATLAB/simulink simulation platform,the simulation results show that, the system has the characteristics of fast response,high precision, strong anti-interference ability etc.. Finally, according to the proposed hybrid control principle, a10kW singlePWM rectifier module experiment platform was set up, hardware of the controlsystem were designed which include sampling circuit, drive and protection circuit,software current and the zero-phase lack circuit, etc; software of the control systemadopt DSP TMS320F2812of TI company as the main control chip. These softwareinclude the main program, strategic control sub-program, SVPWM subroutine andother service-interruptive program. This paper also analysis the data obtained fromthe debugging process of the experiment platform and comes to correspondingconclusion.